Method and apparatus for developing a flight path

ABSTRACT

A method of developing a flight path for precision flying over an area of interest, the method including, in an electronic processing device, determining coordinate and elevation data relating to an area of interest, using the coordinate and elevation data to determine a flight path including precision paths corresponding to precision flying trajectories and non-precision paths interconnecting at least some of the precision paths, and generating path data at least partially indicative of the flight path, the path data being useable in generating control signals for at least partially controlling operation of the aircraft, in use.

BACKGROUND OF THE INVENTION

The present invention relates to a method and apparatus for developing aflight path and a method and apparatus for controlling an aircraft,particularly for use in sensing or deployment within an area ofinterest, for example for infrastructure surveying.

DESCRIPTION OF THE PRIOR ART

The reference in this specification to any prior publication (orinformation derived from it), or to any matter which is known, is not,and should not be taken as an acknowledgment or admission or any form ofsuggestion that the prior publication (or information derived from it)or known matter forms part of the common general knowledge in the fieldof endeavour to which this specification relates.

Surveying of infrastructure, such as roads, powerlines, pipelines, orthe like is problematic as such infrastructure can extend over longdistances and often has limited accessibility. Consequently, these areoften not suitable for manual ground based inspection methods. Whilstcrawling robots have been proposed for inspecting linear infrastructure,these are typically slow and therefore unsuitable for use in inspectinglarge linear infrastructure networks, such as powerline networks, whichinclude over 150,000 km of power lines in Queensland alone.

Consequently, current best practice is to perform aerial surveying usingan aircraft equipped with a suitable sensor, such as LiDAR (LightDetection and Ranging) technology, in a process known as ALSM (AirborneLaser Swath Mapping). However, this also suffers from a number ofdrawbacks.

The complex and distributed nature of network infrastructure typicallyrequires manual generation of flight plans, which are labour intensiveto generate and have a high degree of variability depending on thepreferences and experience of the person doing the planning. Forexample, the planning for small sections of network (<1500 km) oftentakes longer to develop than the actual flight time required for networkcapture.

Additionally, such manual methods also do not lend themselves toassessment of overall flight path lengths or capture of network spurs,meaning the resulting flight paths are often extremely inefficient. Theplanning process also gives little consideration to the sensoroperational parameters relative to aircraft roll angle, meaning it isoften not feasible to capture infrastructure for some planned flightpaths. The planned paths must be flown manually, which coupled with alack of feedback from sensors, means that pilots must maintain theposition of the aircraft to ensure that the infrastructure remains inthe sensor capture footprint, resulting in variable and inefficientimplementation, problems with pilot fatigue and major safety issues.

In an attempt to address some of these issues, a system has beendeveloped for generating 2D off-survey flight paths between manuallydefined on-survey flight paths. The system also allows for limitedcontrol of aircraft position in a 2D plane using existing commercialautopilots. However, the ability of this system is limited as it doesnot consider altitude, pitch or speed control, surrounding terrain, orno-fly regions, such as weather obstacles, or the like. Consequently notall developed flight paths can be flown, and it is still necessary forpilots to control the altitude of the aircraft, which while assisting,does not completely mitigate the extreme burden on the pilot.

Another key limitation of the approach is the necessity to performmanual survey path planning and flight line extraction, which results ininefficiencies in flight planning processes, and in particular does notallow for optimisation of both on and off-survey paths collectively,resulting in efficient flight paths and compromising of inspectionobjectives.

Similarly, precision flying can be required in other situations, such asduring sensing or deployment in an area of interest.

SUMMARY OF THE PRESENT INVENTION

The present invention seeks to substantially overcome, or at leastameliorate, one or more disadvantages of existing arrangements.

In one broad form the invention seeks to provide a method of developinga flight path for precision flying over an area of interest, the methodincluding, in an electronic processing device:

-   -   a) determining coordinate and elevation data relating to an area        of interest;    -   b) using the coordinate and elevation data to determine a flight        path including:        -   i) precision paths corresponding to precision flying            trajectories; and,        -   ii) non-precision paths interconnecting at least some of the            precision paths; and,    -   c) generating path data at least partially indicative of the        flight path, the path data being useable in generating control        signals for at least partially controlling operation of the        aircraft, in use.

Typically the precision paths are for at least one of:

-   -   a) sensing at least part of the area of interest; and,    -   b) deployment into the area of interest.

Typically the method includes controlling the attitude of the aircrafton the precision paths.

Typically the method includes, in the electronic processing device,determining the flight path at least in part using an aircraft flightpath model and at least one of sensor coverage and deploymentparameters.

Typically the method includes, in the electronic processing device:

-   -   a) determining a plurality of candidate precision path sets;    -   b) for each candidate precision path set, determining a        candidate flight path; and,    -   c) selecting a best candidate flight path from the candidate        flight paths.

Typically the method includes, in the electronic processing device, foreach candidate precision path set:

-   -   a) determining non-precision paths between pairs of precision        paths;    -   b) for each possible sequence of precision paths, calculating a        length of a possible flight path; and,    -   c) selecting the possible flight path with the shortest flight        path length as the candidate flight path.

Typically the method includes, in the electronic processing devicedetermining candidate non-precision paths using an aircraft flight pathmodel.

Typically the method includes, in the electronic processing device,using the aircraft flight path model to calculate a candidatenon-precision path using at least one of:

-   -   a) aircraft heading rate constraint and speed;    -   b) an aircraft maximum bank angle;    -   c) an aircraft minimum turn radius;    -   d) a required minimum altitude above the area of interest;    -   e) flight path angle; and    -   f) rate of climb speed of the aircraft.

Typically the method includes, in the electronic processing device:

-   -   a) determining a score for each candidate flight path; and,    -   b) selecting the best candidate flight path using the score.

Typically the method includes, in the electronic process device,determining the score in accordance with at least one of:

-   -   a) intersections with terrain using the elevation data;    -   b) intersections with no-fly zones using no-fly zone data        indicative of the no-fly zones;    -   c) at least one of sensor coverage and deployment parameters;        and,    -   d) a flight path length.

Typically the method includes, in the electronic processing device:

-   -   a) iteratively determining a plurality of best candidate flight        paths; and,    -   b) selecting one of the plurality of best candidate flight paths        as a best flight path.

Typically the method includes, in the electronic processing device,modifying the candidate precision path sets for each iteration.

Typically the method includes, in the electronic processing device, foreach iteration:

-   -   a) comparing a best candidate flight path to a current best        flight path; and,    -   b) selectively updating the current best flight path with the        best candidate flight path depending on the results of the        comparison.

Typically the method includes, in the electronic processing device,iteratively determining best candidate flight paths until at least oneof:

-   -   a) a defined number of iterations have been performed; and,    -   b) a defined tolerance is reached.

Typically the path data includes:

-   -   a) precision segment data indicative of precision paths; and,    -   b) an precision path sequence indicative of an order in which        precision paths should be flown.

Typically the path data is used in controlling at least one of a pitchand altitude of the aircraft in use.

Typically the path data is used in controlling at least one of a roll,yaw, airspeed and engine power of the aircraft in use.

Typically the path data is used in controlling at least one of a sensorand a deployment device.

Typically the method includes, in the electronic processing device:

-   -   a) determining a current aircraft position; and,    -   b) calculating the flight path based on the current aircraft        position.

In one broad form the invention seeks to provide apparatus fordeveloping a flight path for precision flying over an area of interest,the apparatus including an electronic processing device that:

-   -   a) determines coordinate and elevation data relating to an area        of interest;    -   b) uses the coordinate and elevation data to determine a flight        path including:        -   i) precision paths corresponding to precision flying            trajectories; and,        -   ii) non-precision paths interconnecting at least some of the            precision paths; and,    -   c) generates path data at least partially indicative of the        flight path, the path data being useable in generating control        signals for at least partially controlling operation of the        aircraft, in use.

In one broad form the invention seeks to provide a method of controllingan aircraft for precision flying over an area of interest, the methodincluding, in an electronic processing device:

-   -   a) determining path data at least partially indicative of a        flight path, the flight path including precision paths        corresponding to precision flying trajectories and non-precision        paths interconnecting at least some of the precision paths; and,    -   b) generating control signals for at least partially controlling        at least one of the attitude, roll, pitch, speed and altitude of        the aircraft using the path data.

Typically the method includes, in the electronic processing device:

-   -   a) determining coordinate and elevation data relating to an area        of interest;    -   b) using the coordinate and elevation data to determine a flight        path including:        -   i) precision paths corresponding to precision flying            trajectories; and,        -   ii) non-precision paths interconnecting at least some of the            precision paths; and,    -   c) generating path data at least partially indicative of the        flight path, the path data being useable in generating control        signals for at least partially controlling operation of the        aircraft, in use.

Typically the path data includes:

-   -   a) precision segment data indicative of precision paths; and,    -   b) an precision path sequence indicative of an order in which        precision paths should be flown.

Typically the method includes, in the electronic processing device:

-   -   a) determining from the precision segment data, the precision        paths; and,    -   b) generating non-precision paths using an aircraft flight path        model.

Typically the method includes, in the electronic processing device:

-   -   a) determining a current aircraft position;    -   b) determining a flight path segment in accordance with the        current aircraft position; and,    -   c) generating control signals for at least partially controlling        the aircraft using the flight path segment.

Typically the method includes, in the electronic processing device:

-   -   a) determining a current precision path using the current        aircraft position;    -   b) determining at least one next precision path from the path        data; and,    -   c) determining a non-precision path using the current and next        precision paths.

Typically the method includes, in the electronic processing device,providing the control signals to an automated flight control system,thereby allowing the automated flight control system to control theaircraft at least partially in accordance with the control signals.

Typically the method includes, in the automated flight control system,controlling the aircraft in accordance with control signals and userinput commands.

Typically the path data is used in controlling at least one of a roll,yaw, speed and engine power of the aircraft in use.

Typically the method includes, in the electronic processing device:

-   -   a) determining if the aircraft is on an precision path; and,    -   b) selectively activating and deactivating at least one of a        sensor and deployment device depending on results of the        comparison.

Typically the method includes, in the electronic processing device:

-   -   a) monitoring the sensor;    -   b) determining if the area of interest has been sensed; and,    -   c) if not, modifying the flight path.

In one broad form the invention seeks to provide apparatus forcontrolling an aircraft for precision flying over an area of interest,the apparatus including an electronic processing device that:

-   -   a) determines path data at least partially indicative of a        flight path, the flight path including precision paths        corresponding to precision flying trajectories and non-precision        paths interconnecting at least some of the precision paths; and,    -   b) generates control signals for at least partially controlling        at least one of the attitude, roll, pitch, speed and altitude of        the aircraft using the path data.

In one broad form the invention seeks to provide a method of developinga flight path for precision flying over an area of interest, the methodincluding, in an electronic processing device:

-   -   a) determining a flight path by optimising a combination of        precision paths corresponding to precision flying trajectories        and non-precision paths interconnecting at least some of the        precision paths; and,    -   b) generating path data at least partially indicative of the        flight path, the path data being useable in generating control        signals for at least partially controlling operation of the        aircraft, in use.

Typically the method includes, in the electronic processing device:

-   -   a) determining a plurality of candidate precision path sets;    -   b) for each candidate precision path set, determining a        candidate flight path; and,    -   c) selecting a best candidate flight path from the candidate        flight paths.

Typically the method includes, in the electronic processing device, foreach candidate precision path set:

-   -   a) determining non-precision paths between pairs of precision        paths;    -   b) for each possible sequence of precision paths, calculating a        length of a possible flight path; and,    -   c) selecting the possible flight path with the shortest flight        path length as the candidate flight path.

Typically the method includes, in the electronic processing devicedetermining candidate non-precision paths using an aircraft flight pathmodel.

Typically the method includes, in the electronic processing device,using the aircraft flight path model by calculating a candidatenon-precision path using at least one of:

-   -   a) aircraft heading rate constraint and speed;    -   b) an aircraft maximum bank angle;    -   c) an aircraft minimum turn radius;    -   d) a required minimum altitude above the area of interest;    -   e) flight path angle; and    -   f) rate of climb speed of the aircraft.

Typically the method includes, in the electronic processing device:

-   -   a) determining a score for each candidate flight path; and,    -   b) selecting the best candidate flight path using the score.

Typically the method includes, in the electronic process device,determining the score in accordance with at least one of:

-   -   a) intersections with terrain using the elevation data;    -   b) intersections with no-fly zones using no-fly zone data        indicative of the no-fly zones;    -   c) at least one of sensor coverage and deployment parameters;        and,    -   d) a flight path length.

Typically the method includes, in the electronic processing device:

-   -   a) iteratively determining a plurality of best candidate flight        paths; and,    -   b) selecting one of the plurality of best candidate flight paths        as a best flight path.

Typically the method includes, in the electronic processing device,modifying the candidate precision path sets for each iteration.

Typically the method includes, in the electronic processing device, foreach iteration:

-   -   a) comparing a best candidate flight path to a current best        flight path; and,    -   b) selectively updating the current best flight path with the        best candidate flight path depending on the results of the        comparison.

Typically the method includes, in the electronic processing device,iteratively determining best candidate flight paths until at least oneof:

-   -   a) a defined number of iterations have been performed; and,    -   b) a defined tolerance is reached.

In one broad form the invention seeks to provide apparatus fordeveloping a flight path for precision flying over an area of interest,the apparatus including an electronic processing device that:

-   -   a) determines a flight path by optimising a combination of        precision paths corresponding to precision flying trajectories        and non-precision paths interconnecting at least some of the        precision paths; and,    -   b) generates path data at least partially indicative of the        flight path, the path data being useable in generating control        signals for at least partially controlling operation of the        aircraft, in use.

In one broad form the invention seeks to provide a method of developinga flight path for infrastructure surveying by an aircraft, the methodincluding, in an electronic processing device:

-   -   a) determining coordinate and elevation data relating to        infrastructure to be surveyed;    -   b) using the coordinate and elevation data to determine a flight        path including:        -   i) on-survey paths corresponding to infrastructure segments;            and,        -   ii) off-survey paths interconnecting at least some of the            on-survey paths; and,    -   c) generating path data at least partially indicative of the        flight path, the path data being useable in generating control        signals for at least partially controlling operation of the        aircraft, in use.

Typically the method includes, in the electronic processing device:

-   -   a) identifying infrastructure segments from the coordinate data;    -   b) grouping the infrastructure segments; and,    -   c) determining a flight path for each group of infrastructure        segments.

Typically the method includes grouping the infrastructure segments inaccordance with at least one of a flight time and flight distancerequirement.

Typically the method includes, in the electronic processing device,determining the flight path at least in part using an aircraft flightpath model and sensor coverage parameters.

Typically the method includes, in the electronic processing device:

-   -   a) determining a plurality of candidate on-survey path sets;    -   b) for each candidate on-survey path set, determining a        candidate flight path; and,    -   c) selecting a best candidate flight path from the candidate        flight paths.

Typically the method includes, in the electronic processing device, foreach candidate on-survey path set:

-   -   a) determining off-survey paths between pairs of on-survey        paths;    -   b) for each possible sequence of on-survey paths, calculating a        length of a possible flight path; and,    -   c) selecting the possible flight path with the shortest flight        path length as the candidate flight path.

Typically the method includes, in the electronic processing devicedetermining candidate off-survey paths using an aircraft flight pathmodel.

Typically the method includes, in the electronic processing device,using the aircraft flight path model to calculate a candidate off-surveypath using at least one of:

-   -   a) aircraft heading rate constraint and speed;    -   b) an aircraft maximum bank angle;    -   c) an aircraft minimum turn radius;    -   d) a required minimum altitude above terrain and infrastructure;    -   e) flight path angle; and    -   f) rate of climb speed of the aircraft.

Typically the method includes, in the electronic processing device:

-   -   a) determining a score for each candidate flight path; and,    -   b) selecting the best candidate flight path using the score.

Typically the method includes, in the electronic process device,determining the score in accordance with at least one of:

-   -   a) intersections with terrain using the elevation data;    -   b) intersections with no-fly zones using no-fly zone data        indicative of the no-fly zones;    -   c) infrastructure sensor coverage; and,    -   d) a flight path length.

Typically the method includes, in the electronic processing device:

-   -   a) iteratively determining a plurality of best candidate flight        paths; and,    -   b) selecting one of the plurality of best candidate flight paths        as a best flight path.

Typically the method includes, in the electronic processing device,modifying the candidate on-survey path sets for each iteration.

Typically the method includes, in the electronic processing device, foreach iteration:

-   -   a) comparing a best candidate flight path to a current best        flight path; and,    -   b) selectively updating the current best flight path with the        best candidate flight path depending on the results of the        comparison.

Typically the method includes, in the electronic processing device,iteratively determining best candidate flight paths until at least oneof:

-   -   a) a defined number of iterations have been performed; and,    -   b) a defined tolerance is reached.

Typically the path data includes:

-   -   a) on-survey segment data indicative of on-survey paths; and,    -   b) an on-survey path sequence indicative of an order in which        on-survey paths should be flown.

Typically the path data is used in controlling at least one of a pitchand altitude of the aircraft in use.

Typically the path data is used in controlling at least one of a roll,yaw, airspeed and engine power of the aircraft in use.

Typically the path data is used in controlling a sensor for sensing theinfrastructure.

Typically the method includes, in the electronic processing device:

-   -   a) determining a current aircraft position; and,    -   b) calculating the flight path based on the current aircraft        position.

In one broad form the invention seeks to provide apparatus fordeveloping a flight path for infrastructure surveying by an aircraft,the apparatus including an electronic processing device that:

-   -   a) determines coordinate and elevation data relating to        infrastructure to be surveyed;    -   b) uses the coordinate and elevation data to determine a flight        path including:        -   i) on-survey paths corresponding to infrastructure segments;            and,        -   ii) off-survey paths interconnecting at least some of the            on-survey paths; and,    -   c) generates path data at least partially indicative of the        flight path, the path data being useable in generating control        signals for at least partially controlling operation of the        aircraft, in use.

In one broad form the invention seeks to provide a method of controllingan aircraft for infrastructure surveying, the method including, in anelectronic processing device:

-   -   a) determining path data at least partially indicative of a        flight path, the flight path including on-survey paths        corresponding to infrastructure segments and off-survey paths        interconnecting at least some of the on-survey paths; and,    -   b) generating control signals for at least partially controlling        at least one of the pitch, speed and altitude of the aircraft        using the path data.

Typically the method includes, in the electronic processing device:

-   -   a) determining coordinate and elevation data relating to        infrastructure to be surveyed;    -   b) using the coordinate and elevation data to determine a flight        path including:        -   i) on-survey paths corresponding to infrastructure segments;            and,        -   ii) off-survey paths interconnecting at least some of the            on-survey paths; and,    -   c) generating path data at least partially indicative of the        flight path, the path data being useable in generating control        signals for at least partially controlling operation of the        aircraft, in use.

Typically the path data includes:

-   -   a) on-survey segment data indicative of on-survey paths; and,    -   b) an on-survey path sequence indicative of an order in which        on-survey paths should be flown.

Typically the method includes, in the electronic processing device:

-   -   a) determining from the on-survey segment data, the on-survey        paths; and,    -   b) generating off-survey paths using an aircraft flight path        model.

Typically the method includes, in the electronic processing device:

-   -   a) determining a current aircraft position;    -   b) determining a flight path segment in accordance with the        current aircraft position; and,    -   c) generating control signals for at least partially controlling        the aircraft using the flight path segment.

Typically the method includes, in the electronic processing device:

-   -   a) determining a current on-survey path using the current        aircraft position;    -   b) determining at least one next on-survey path from the path        data; and,    -   c) determining an off-survey path using the current and next        on-survey paths.

Typically the method includes, in the electronic processing device,providing the control signals to an automated flight control system,thereby allowing the automated flight control system to control theaircraft at least partially in accordance with the control signals.

Typically the method includes, in the automated flight control system,controlling the aircraft in accordance with control signals and userinput commands.

Typically the path data is used in controlling at least one of a roll,yaw, speed and engine power of the aircraft in use.

Typically the method includes, in the electronic processing device:

-   -   a) determining if the aircraft is on an on-survey path; and,    -   b) selectively activating and deactivating a sensor depending on        results of the comparison.

Typically the method includes, in the electronic processing device:

-   -   a) monitoring the sensor;    -   b) determining if the infrastructure has been sensed; and,    -   c) if not, modifying the flight path.

In one broad form the invention seeks to provide apparatus forcontrolling an aircraft for infrastructure surveying, the apparatusincluding an electronic processing device that:

-   -   a) determines path data at least partially indicative of a        flight path, the flight path including on-survey paths        corresponding to infrastructure segments and off-survey paths        interconnecting at least some of the on-survey paths; and,    -   b) generates control signals for at least partially controlling        at least one of the pitch, speed and altitude of the aircraft        using the path data.

In one broad form the invention seeks to provide a method of developinga flight path for infrastructure surveying by an aircraft, the methodincluding, in an electronic processing device:

-   -   a) determining a flight path by optimising a combination of        on-survey paths corresponding to infrastructure segments and        off-survey paths interconnecting at least some of the on-survey        paths; and,    -   b) generating path data at least partially indicative of the        flight path, the path data being useable in generating control        signals for at least partially controlling operation of the        aircraft, in use.

Typically the method includes, in the electronic processing device:

-   -   a) determining a plurality of candidate on-survey path sets;    -   b) for each candidate on-survey path set, determining a        candidate flight path; and,    -   c) selecting a best candidate flight path from the candidate        flight paths.

Typically the method includes, in the electronic processing device, foreach candidate on-survey path set:

-   -   a) determining off-survey paths between pairs of on-survey        paths;    -   b) for each possible sequence of on-survey paths, calculating a        length of a possible flight path; and,    -   c) selecting the possible flight path with the shortest flight        path length as the candidate flight path.

Typically the method includes, in the electronic processing devicedetermining candidate off-survey paths using an aircraft flight pathmodel.

Typically the method includes, in the electronic processing device,using the aircraft flight path model by calculating a candidateoff-survey path using at least one of:

-   -   a) aircraft heading rate constraint and speed;    -   b) an aircraft maximum bank angle;    -   c) an aircraft minimum turn radius;    -   d) a required minimum altitude above terrain and infrastructure;    -   e) flight path angle; and    -   f) rate of climb speed of the aircraft.

Typically the method includes, in the electronic processing device:

-   -   a) determining a score for each candidate flight path; and,    -   b) selecting the best candidate flight path using the score.

Typically the method includes, in the electronic process device,determining the score in accordance with at least one of:

-   -   a) intersections with terrain using the elevation data;    -   b) intersections with no-fly zones using no-fly zone data        indicative of the no-fly zones;    -   c) infrastructure sensor coverage; and,    -   d) a flight path length.

Typically the method includes, in the electronic processing device:

-   -   a) iteratively determining a plurality of best candidate flight        paths; and,    -   b) selecting one of the plurality of best candidate flight paths        as a best flight path.

Typically the method includes, in the electronic processing device,modifying the candidate on-survey path sets for each iteration.

Typically the method includes, in the electronic processing device, foreach iteration:

-   -   a) comparing a best candidate flight path to a current best        flight path; and,    -   b) selectively updating the current best flight path with the        best candidate flight path depending on the results of the        comparison.

Typically the method includes, in the electronic processing device,iteratively determining best candidate flight paths until at least oneof:

-   -   a) a defined number of iterations have been performed; and,    -   b) a defined tolerance is reached.

In one broad form the invention seeks to provide apparatus fordeveloping a flight path for infrastructure surveying by an aircraft,the apparatus including an electronic processing device that:

-   -   a) determines a flight path by optimising a combination of        on-survey paths corresponding to infrastructure segments and        off-survey paths interconnecting at least some of the on-survey        paths; and,    -   b) generates path data at least partially indicative of the        flight path, the path data being useable in generating control        signals for at least partially controlling operation of the        aircraft, in use.

It will be appreciated that the broad forms of the invention can be usedindependently, or in conjunction and that features of the broad formscan be used interchangeably.

BRIEF DESCRIPTION OF THE DRAWINGS

An example of the present invention will now be described with referenceto the accompanying drawings, in which:—

FIG. 1 is a flowchart of an example of a method for developing a flightpath for precision flying and a method of controlling an aircraft forprecision flying;

FIG. 2 is a schematic diagram of an example of a distributed computerarchitecture;

FIG. 3 is a schematic diagram of an example of a processing system;

FIG. 4 is a schematic diagram of an example of a computer system;

FIGS. 5A to 5C are a flowchart of an example of a method of developing aflight path for infrastructure surveying by an aircraft;

FIG. 5D is an image of example infrastructure segments;

FIG. 5E is a schematic diagram illustrating example sensor coverage foran aircraft;

FIG. 6 is a schematic diagram of an example of an aircraft controlsystem;

FIGS. 7A and 7B are a flowchart of an example of a method forcontrolling an aircraft;

FIG. 7C is a schematic diagram of an example of a user interface; and,

FIG. 8 is a schematic diagram of the functionality of a system fordeveloping and flying a flight path for infrastructure surveying.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A method of developing a flight path and a method of controlling anaircraft for precision flying, such as infrastructure surveying, willnow be described with reference to FIG. 1.

In this example, it is assumed that the process is performed at least inpart using an electronic processing device forming part of a processingsystem, which may be connected to one or more other computer systems viaa network architecture.

It is also further assumed that control of the aircraft is typicallyperformed using a flight control system, such as a commercial autopilot,with an electronic processing device in communication with the flightcontrol system. In this regard, the electronic processing device usedfor developing the flight plan and communicating with the flight controlsystem may be the same electronic processing device or may be differentelectronic processing devices, as will be described in more detailbelow.

The term “precision flying” refers to flying in a controlled manneralong a defined trajectory with control of at least the position andattitude of the aircraft, as well as other optional constraints such asvelocity, rate of change of attitude, or the like, such that at leastposition and attitude is controlled to within a desired tolerance of atleast specified position and attitude constraints. Precision flying canbe used for sensing within an area of interest, either forinfrastructure sensing, as will be described in more detail below, butalso for other applications, such as searching or data collection, aswell as for deployment, for example in spraying, package deliveryapplications or the like.

The term “infrastructure” is intended to cover any physical asset,facility or structure, and more typically a structure that extends overa distance of at least one kilometre, and more typically over tens orhundreds of kilometres. The infrastructure may include a singlestructure, or a network of multiple connected or unconnected structures,and can include, but is not limited to, power lines, telecommunicationslines, pipelines, roadways, railways, canals, fences, or the like.

In this example, at step 100, the electronic processing devicedetermines coordinate and elevation data relating to an area of interestand/or to infrastructure to be surveyed. The nature of the coordinateand elevation data may vary depending upon the preferred implementation.In one example, the coordinate and elevation data are separate datasets, but this is not essential, and a single combined data set could beused.

The coordinate data may specify coordinates of particular parts of anarea of interest, such as extents of a boundary, or the like. Similarly,the coordinate data may specify coordinates of particular parts of aninfrastructure, so for power lines for example, the coordinates mayspecify the location of transmission towers, power line poles, or othersupporting structures. The elevation data may relate only to theelevation of particular parts of the infrastructure, but typicallyrelates to the elevation of the terrain in the area of interest, whichcan be a region immediately surrounding the infrastructure and moretypically to entire flight region. Thus, it will be appreciated that theelevation data may include terrain information from terrain model,mapping survey, or the like.

The coordinate and elevation data may be determined in any appropriatemanner. In one example, the data is stored in a store, such as a remotedatabase and accessed by the electronic processing device as needed.However, this is not essential and alternatively the coordinate andelevation data may be received by the electronic processing device via acommunications network, received from sensor information or satelliteimages, or wholly or partially entered by a user.

At step 110 the electronic processing device uses the coordinate andelevation data to determine a flight path including a combination ofprecision and non-precision paths. In this regard, the precision pathscorrespond to precision flying trajectories, whilst the non-precisionpaths interconnect the precision flying trajectories and typically havea reduced tolerance in terms of attitude and/or altitude requirements.In this regard, the precision path is a portion of the flight pathduring which precision flying is being performed, for example for thepurpose of sensing or deployment. The precision path is typicallyplanned as part of an overall sequence of precision paths, allowing anoverall sensing or deployment requirement to be met. Thus, for example,in sensing, this could correspond to overflying an entire area so as toallow the whole area to be imaged, for example for surveying the area,performing searching, or the like. In deployment, an entire area mayneed to be covered, for example when spraying an area, for example incrop spraying or oil dispersion applications, or only specific parts ofthe area, for example if supplies are being dropped from an aircraftinto a relief zone, or water bombing a bush fire, or the like. Ingeneral, when flying on a precision flight path, this requires that atleast the position and attitude of the aircraft is controlled to ensuretargeted sensing or deployment.

In contrast, the non-precision paths are used to connect the precisionflight paths and consequently, the same degree of tolerance to desiredconstraints is not required.

When surveying infrastructure, the precision and non-precision pathsequate to on-survey paths corresponding to infrastructure segments andoff-survey paths interconnecting at least some of the on-survey paths.In this regard, the term on-survey path is generally used to refer toany portion of the flight path where the aircraft is overflying theinfrastructure, or is overflying the infrastructure for a majority ofthe time. Consequently, on-survey paths correspond to section of theflight path for which a sensor, such as LiDAR sensor, is activated tothereby sense the infrastructure. It will be appreciated that theon-survey paths may include short segments where there is noinfrastructure present, such as if an aircraft is flying perpendicularlyacross parallel spaced apart power lines, or the like. In one preferredexample, the on-survey paths generally correspond to segments of theinfrastructure, and in one particular example substantially linearsegments, although this is not essential, as will be described in moredetail below.

The off-survey paths correspond to sections of flight path thatinterconnect on-survey paths and for which the sensor is typicallydeactivated. Whilst all of the on-survey paths may be interconnected byoff-survey paths, this is not essential and in some examples, on-surveypaths may be effectively directly interconnected. This may occur, forexample, if the on-survey paths correspond to linear segments, andlinear segments are in abutment with only a minor change in directiontherebetween, although this could also be considered as a singlenon-linear on-survey path. This can be achieved by directlyinterconnecting the on-survey segments, but more typically this isachieved as part of the optimisation process by providing aninterconnecting off-survey path having a zero or near zero path length.

The flight path can be determined in any appropriate manner, but this istypically achieved by having the electronic processing device determinepotential sequences of precision or on-survey paths, generatenon-precision or off-survey paths between at least some of the precisionor on-survey paths, and then perform an optimisation process on both theprecision or on-survey and non-precision or off-survey paths, to therebydetermine the flight path. The optimisation process can be performed toreduce the flight path length whilst also meeting other requirements,such as to avoid intersections with terrain or no-fly zones, whilst alsoensuring adequate sensor coverage of the infrastructure.

At step 120, the electronic processing device generates path data atleast partially indicative of the flight path, the flight path databeing useable in generating control segments for at least partiallycontrolling operation of the aircraft in use. The flight path data canbe of any appropriate form, and can include control signals for anaircraft flight control system, information regarding sequences ofprecision and non-precision or on-survey and off-survey segments, butmore typically includes a sequence of precision or on-survey segmentsallowing non-precision or off-survey sequences to be calculated duringflight.

The above steps may be performed by an electronic processing device thatis ground based with this being performed as a part of a flight planningstep prior to implementation by an aircraft. In this instance, the pathdata can then be transferred to an aircraft, for example using asuitable communication technique such as wireless transfer via acommunications network, or transfer on physical media such as a USB(Universal Serial Bus) storage device, or the like. Alternatively, theflight path may be calculated on board and stored for use as required,or generated dynamically during flight.

In the event that the flight path data is previously determined, at step130 the aircraft electronic processing device determines the path data,which as mentioned above, is at least indicative of the flight path.Thus, this may involve retrieving the flight path from a store, orcalculating the flight as outlined above with respect to steps 100 to120 above.

At step 140 the aircraft electronic processing device generates controlsignals for at least partially controlling at least one of the attitude,pitch and altitude of the aircraft using the path data. As part of thisprocess, the aircraft electronic processing device may need to generateinformation regarding the flight path, so for example, this couldinclude calculating non-precision or off-survey segments from precisionor on-survey segments, respectively. Furthermore, this may be performedat least partially based on a current aircraft position, as will bedescribed in more detail below.

Whilst the above described process is described as being performed by aground based electronic processing device and a separate aircraft basedelectronic processing device this is not essential and alternatively, asingle aircraft based electronic processing device can be used toperform each of steps 100 to 140 as will be described in more detailbelow.

In any event, in the above described process, and in contrast totraditional techniques, the method includes taking into accountelevation data during the flight path development phase. By taking intoaccount elevation data, this allows one or more of the speed (such asthe air speed or ground speed), pitch or altitude of the aircraft to becontrolled, which cannot be achieved using either traditional manual or2D flight planning techniques. This in turn allows an autopilot or otherflight control system to take control of one or more of the aircraftspeed, altitude or pitch, reducing the mental burden on the pilot. Thisin turn makes it easier for the pilot to monitor operation of theaircraft and allowing the pilot to fly for longer periods of time. Thisvastly enhances the rate at which infrastructure can be surveyed.

A further benefit of utilising elevation data is that this allows theplanning process to exclude flight paths that would intersect withterrain, which would not necessarily be excluded using traditionaltechniques.

In addition, in the above described techniques, the electronicprocessing device uses coordinate and elevation data to generate bothprecision and non-precision or on-survey and off-survey paths. This isin contrast to traditional techniques in which the precision oron-survey paths are defined manually. Calculating both the on andoff-survey paths as part of the same planning process allows bothon-survey and off-survey segments to be optimised in conjunction, whichin turn leads to unexpected benefits, in some instance resulting insignificantly shorter flight paths whilst covering the same amount ofinfrastructure. This can be achieved using flight paths that would beexcluded under previous planning regimes, as will be described in moredetail below.

Accordingly, it will be appreciated that the above described planningand control processes offer significant advantages over existing flightpath planning and execution techniques.

A number of further features will now be described.

Typically the precision paths are for at least one of sensing at leastpart of the area of interest and deployment into the area of interest.The method generally includes controlling at least the attitude andposition of the aircraft on the precision paths.

It will be appreciated from the above that infrastructure surveying isone specific example of precision flying. For the purpose of ease ofexplanation, the following description will focus on surveying ofinfrastructure. However, it will be appreciated that this is one exampleand is not intended to be limiting. Consequently any techniques forinfrastructure surveying can be applied to precision flying, and theseexamples should therefore be considered interchangeably, with the termsprecision path and non-precision path being considered equivalent toon-survey and off-survey paths, respectively.

In one example the method of developing a flight path includes, in theelectronic processing device, identifying infrastructure segments fromthe coordinate data, grouping the infrastructure segments anddetermining a flight path for each group of infrastructure segments.This is typically performed to group infrastructure segments intomissions that are feasible for an aircraft and pilot to fly. Thegrouping can be achieved in any suitable manner but is typically basedon at least one of a flight time and flight distance requirement, andmay also depend on other factors, such as vicinities to airfields or thelike. Thus, a total length of the infrastructure segments, or time takento fly the infrastructure segments, can be used to select a number ofsegments that can be combined to form a given mission. It will beappreciated that this allows the mapping of a large region to be brokendown into individual missions, simplifying the task of planning theflight path.

In one example, the flight path is determined by the electronicprocessing device in part using an aircraft flight path model and atleast one of sensor coverage and deployment parameters. The aircraftflight path model can be any form of model that can be used to model theaircraft flight capabilities and can include a geometric path model(such as simply lines and curves for paths), through to a fullaerodynamic model that takes into account flight capabilities of theaircraft, such as the maximum and minimum bank and turn angles, usingthese to place limitations on the flight path that can be calculated.Additionally the sensor coverage parameters are used to restrict theorientation of the aircraft relative to the infrastructure to ensurethat the infrastructure is positioned within a sensor footprint, such asthe lateral extent of an ALSM sensor as defined by the sensor field ofview, allowing this to be taken into account to ensure that allinfrastructure is covered by the survey. It will be appreciated thatsimilar techniques could be used for other sensing applications, or fordetermining precision paths using deployment parameters for a deploymentapplication,

The process of determining the flight path typically involves having theelectronic processing device determine a plurality of candidateon-survey path sets, determining a candidate flight path for eachcandidate on-survey path set and selecting the best candidate flightpath from the candidate flight paths. Thus, multiple candidate on-surveypath sets can be created and used to allow multiple candidate flightpaths to be determined, with a best one of these then being selected.This allows an iterative process to be performed in which differentoverlapping on-survey paths sets are defined, with these beingrepeatedly modified in order to maximise the chance of a shortestoptimum flight path being identified.

The process for determining a candidate flight path for each on-surveypath set typically involves having the electronic processing devicedetermine off-survey paths between pairings of on-survey paths withinthe set, for each possible sequence of on-survey paths calculating aflight path length and then selecting a flight path with the shortestflight path length as the candidate flight path, for the respectiveon-survey path set. Thus, it will be appreciated that this process willcalculate possible off-survey paths between the on-survey paths and thenuse possible sequences of on-survey paths to calculate an overall pathlength. The possible sequences of on-survey paths can include pathswhere on-survey paths are effectively interconnected directly using anintervening off-survey path having a zero or minimal path length. Thus,there are multiple on-survey path sets with each one of these being usedto identify a number of possible flight paths, with best one of thesebeing selected to represent the candidate flight path for each set.

In this process, the off-survey paths are determined using the aircraftflight path model, which takes into account one or more of an aircraftheading rate constraint and speed, an aircraft maximum bank angle, anaircraft minimum turn radius, a required minimum altitude above an areaof interest, or terrain and infrastructure, a flight path angle and rateof climb speed of the aircraft.

In general, the best candidate flight path is identified by determininga score for the candidate flight path from each on-survey path set andthen selecting the best candidate flight path using the score. The scorecan be calculated taking into account one or more of intersections withterrain using the terrain data, intersections with no-fly zones usingno-fly data indicative of no-fly zones, sensor or deployment devicecoverage, and a flight path length.

The above described steps are typically performed iteratively, with eachiteration being based on different on-survey path sets. In this example,the process involves repeatedly determining a plurality of candidateflight paths, and each time selecting a new best candidate flight path.The new best candidate flight path is then compared to a current bestflight path determined during a previous iteration, with the currentbest flight path being updated with the new best candidate flight path,depending on the results of the comparison. This process can beperformed repeatedly until a stop condition is reached, such as when aset number of iterations have been performed, or until no additionalimprovement is identified, at which point the current best flight pathis identified as the preferred flight path.

Once a preferred flight path has been identified, the electronicprocessing device generates the path data which typically includeson-survey segment data indicative of on-survey paths and an on-surveypath sequence indicative of an order in which the on-survey paths shouldbe flown. In this regard, it is not necessary to include off-surveypaths in the flight data as these can be calculated during flight.Whilst this increases the computational load on the electronicprocessing device in the aircraft, as the on-survey segments and theorder on which they are flown has previously been determined, thecalculation of off-survey flight paths is relatively straightforward,using the aircraft flight path model. It will also be appreciated thatin any event the ability to calculate flight paths during flight isimportant in case there are deviations of the aircraft from the intendedflight path.

The flight path data can be used in controlling the pitch and altitudeof the aircraft, as well as the roll, yaw, engine power or the like. Thepath data can also be used for controlling a sensor, for example byensuring the sensor is active when flying on-survey paths and inactivewhen flying off-survey paths. Similar techniques could also be appliedto control of a deployment device on precision paths.

In use, the electronic processing device will typically determine acurrent aircraft position and then calculate the flight path based onthe current aircraft position. This allows the aircraft to take intoaccount deviation of the aircraft from the planned flight path, as wellas to allow go-arounds or the like if infrastructure or part of an areaof interest is missed. In order to achieve this, the aircraft electronicprocessing device will typically determine a current aircraft position,determine a flight path segment in accordance with the current aircraftposition and then generate control signals for at least partiallycontrolling the aircraft using the flight path segment. In performingthis operation the electronic processing device will determine a currenton-survey path using the current aircraft position, determine one ormore next on-survey paths from path data and then determine anyoff-survey paths connecting the current and next on-survey paths usingthe aircraft flight path model. In this regard, if the paths are shortit will be typical to plan two, three or more paths ahead.

In use, the electronic processing device typically provides controlsignals to a flight control system, such as a commercial autopilot,allowing the flight control system to control the aircraft at leastpartially in accordance with the control signals. In this regard, itwill be appreciated that commercial flight control systems exist thatare capable of controlling aspects of aircraft flight includingaltitude, pitch, roll, yaw, speed or the like, based on received inputcommands. By allowing the electronic processing device to interface withan existing flight control system this simplifies the process ofimplementing the flight control process in an existing aircraft. Forexample, this allows existing certified equipment to be used for actualcontrol of the aircraft, thereby facilitating a simpler certificationprocess for the electronic processing device. It will also beappreciated that the aircraft can also be further equipped with othersafety systems such as stall-inhibitors, terrain anti-collision devices,or the like, and that these will remain unaffected by the electronicprocessing device.

Additionally, the electronic processing device can be adapted todetermine if the aircraft is on an on-survey path and then selectivelyactivate and deactivate a sensor depending on the results of thecomparison. Thus, this process allows the electronic processing deviceto automatically activate and deactivate the sensor upon entering ontoor leaving an on-survey path, respectively. Consequently, the sensor isonly used on on-survey paths, thereby reducing the amount of datacollected, whilst ensuring that data is sensed for the entirety of theinfrastructure. Similar techniques could also be applied to control of adeployment device on precision paths.

Additionally, the electronic processing device can also operate tomonitor the sensor, determine if infrastructure has been sensed, and ifnot modify the flight path. In this regard, the sensor can be adapted todetect when sensing of infrastructure has been missed and trigger ago-around to ensure the infrastructure has been correctly captured.

In one example, the above described flight planning process can beperformed by one or more processing systems operating as part of adistributed architecture, an example of which will now be described withreference to FIG. 2.

In this example, the arrangement includes a number of processing systems201 and computer systems 203 interconnected via one or morecommunications networks, such as the Internet 202, and/or a number oflocal area networks (LANs) 204. It will be appreciated that theconfiguration of the networks 202, 204 is for the purpose of exampleonly, and in practice the processing and computer systems 201, 203 cancommunicate via any appropriate mechanism, such as via wired or wirelessconnections, including, but not limited to mobile networks, privatenetworks, such as an 802.11 networks, the Internet, LANs, WANs, or thelike, as well as via direct or point-to-point connections, such asBluetooth, or the like.

The use of separate terms “processing system” and “computer system” isfor illustrative purposes and to enable distinction between differentdevices, optionally having different functionality. For example, theprocessing and computer systems 201, 203 could represent servers andclients respectively, as will become apparent from the followingdescription. However, this is not intended to be limiting and inpractice any suitable computer network architecture can be used.

An example of a suitable processing system 201 is shown in FIG. 3. Inthis example, the processing system 201 includes an electronicprocessing device, such as at least one microprocessor 300, a memory301, an optional input/output device 302, such as a keyboard and/ordisplay, and an external interface 303, interconnected via a bus 304 asshown. In this example the external interface 303 can be utilised forconnecting the processing system 201 to peripheral devices, such as thecommunications networks 202, 204, databases 211, other storage devices,or the like. Although a single external interface 303 is shown, this isfor the purpose of example only, and in practice multiple interfacesusing various methods (eg. Ethernet, serial, USB, wireless or the like)may be provided.

In use, the microprocessor 300 executes instructions in the form ofapplications software stored in the memory 301 to perform requiredprocesses, such as communicating with other processing or computersystems 201, 203. Thus, actions performed by a processing system 201 areperformed by the processor 300 in accordance with instructions stored asapplications software in the memory 301 and/or input commands receivedvia the I/O device 302, or commands received from other processing orcomputer systems 201, 203. The applications software may include one ormore software modules, and may be executed in a suitable executionenvironment, such as an operating system environment, or the like.

Accordingly, it will be appreciated that the processing systems 201 maybe formed from any suitable processing system, such as a suitablyprogrammed computer system, PC, web server, network server, or the like.In one particular example, the processing systems 201 are standardprocessing system such as a 32-bit or 64-bit Intel Architecture basedprocessing system, which executes software applications stored onnon-volatile (e.g., hard disk) storage, although this is not essential.However, it will also be understood that the processing system could beor could include any electronic processing device such as amicroprocessor, microchip processor, logic gate configuration, firmwareoptionally associated with implementing logic such as an FPGA (FieldProgrammable Gate Array), or any other electronic device, system orarrangement.

As shown in FIG. 4, in one example, the computer systems 203 include anelectronic processing device, such as at least one microprocessor 400, amemory 401, an input/output device 402, such as a keyboard and/ordisplay, and an external interface 403, interconnected via a bus 404 asshown. In this example the external interface 403 can be utilised forconnecting the computer system 203 to peripheral devices, such as thecommunications networks 202, 204, databases, other storage devices, orthe like. Although a single external interface 403 is shown, this is forthe purpose of example only, and in practice multiple interfaces usingvarious methods (eg. Ethernet, serial, USB, wireless or the like) may beprovided.

In use, the microprocessor 400 executes instructions in the form ofapplications software stored in the memory 401 to perform requiredprocesses, for example to allow communication with other processing orcomputer systems 201, 203. Thus, actions performed by a processingsystem 203 are performed by the processor 400 in accordance withinstructions stored as applications software in the memory 401 and/orinput commands received from a user via the I/O device 402. Theapplications software may include one or more software modules, and maybe executed in a suitable execution environment, such as an operatingsystem environment, or the like.

Accordingly, it will be appreciated that the computer systems 203 may beformed from any suitable processing system, such as a suitablyprogrammed PC, Internet terminal, lap-top, hand-held PC, smart phone,PDA, tablet, or the like. Thus, in one example, the processing system300 is a standard processing system such as a 32-bit or 64-bit IntelArchitecture based processing system, which executes softwareapplications stored on non-volatile (e.g., hard disk) storage, althoughthis is not essential. However, it will also be understood that theprocessing systems 203 can be any electronic processing device such as amicroprocessor, microchip processor, logic gate configuration, firmwareoptionally associated with implementing logic such as an FPGA (FieldProgrammable Gate Array), or any other electronic device, system orarrangement.

It will also be noted that whilst the processing and computer systems201, 203 are shown as single entities, it will be appreciated that thisis not essential, and instead one or more of the processing and/orcomputer systems 201, 203 can be distributed over geographicallyseparate locations, for example by using processing systems provided aspart of a cloud based environment.

In one example, the processing system 201 is used to calculate theflight path, with this being transferred to one of the computer systems203, for subsequent transfer to an onboard aircraft computer system. Itwill also be assumed that the user interacts with the processing systemvia a GUI (Graphical User Interface), or the like, presented on the usercomputer system 203.

However, it will be appreciated that the above described configurationassumed for the purpose of the following examples is not essential, andnumerous other configurations may be used. It will also be appreciatedthat the partitioning of functionality between the processing andcomputer systems 201, 203 may vary, depending on the particularimplementation, so that for example, the flight planning method could beperformed solely on the computer system 203, which may or may not becoupled to a communications system. Alternatively, the computer system203 can represent the onboard aircraft electronic processing device,coupled to a processing system 201 that operates to plan the flightpath.

A second example of a method of developing a flight path forinfrastructure surveying by an aircraft will now be described withreference 5A to 5E.

In this example, at step 500 the electronic processing device 201obtains infrastructure coordinates and elevation data, typically byretrieving these from the database 211 or receiving them from one ormore remote processing or computer systems, via one of thecommunications networks 202, 204. An example power line infrastructureis shown in FIG. 5D, and in one example, the coordinates represent thelocation of transmission towers. The elevation data may be of any form,but is typically a digital elevation model (DEM), digital terrain model(DTM), digital surface model (DSM) or the like, and may be obtained fromsurvey and/or remote sensing of terrain in the region containing theinfrastructure.

At step 505, the processing system 201 identifies infrastructuresegments within the infrastructure coordinates, and then groups thesesegments into missions at step 510. Grouping into missions is performedto define a limited dataset of segments for which flight path planningand optimisation can be feasibly performed, as well as to allow forindividual flight paths to be defined that can be reasonably flown by apilot without undue fatigue. The grouping can be performed on the basisof any suitable criteria, such as a number or total length of theinfrastructure segments, and may also take into account other factors,such as the flight time of the segments, the distance from an airfield,and hence the round trip flight time. It will be appreciated that thisis also typically based to some extent on the location of theinfrastructure segments, ensuring that the infrastructure segments in agiven common area are assigned to a common mission. The grouping can beperformed in any suitable manner and can use a known clusteringalgorithm or the like.

At step 515, for each mission, the processing system 201 determinescandidate sets of on-survey paths. The on-survey paths are typicallyrepresented by agents that are designed to be used in a suitableoptimisation algorithm and may therefore be in the form of cooperativeoptimisation agents (analogous to genes, fireflies, or the like),depending on the nature of the optimisation algorithm used, as will bedescribed in more detail below.

At step 520, the processing system 201 determines off-survey paths usingan aircraft flight path model for each candidate set. The off-surveypaths are determined for each possible pairing of on-survey paths withinthe set, and for each possible direction of travel along the on-surveypaths. Following this, at step 525 the electronic processing devicedetermines possible flight paths for each possible sequence of on-surveypaths, including on-survey paths in reverse directions, and using theoff-survey paths generated at step 520 to link the on-survey paths.

The processing system 201 then determines the length of each of thesepossible flight paths, and selects a best one of the possible flightpath to form the candidate flight path for each set at step 535.Typically each iteration of the algorithm will use fifteen or so sets,in which case, at this point fifteen candidate flight paths areidentified, although it will be appreciated that any suitable number canbe used.

The next stage is for the processing system 201 to evaluate which ofthese candidate flight paths is the best candidate flight path for thecurrent iteration. The evaluation takes into account not only the lengthof the candidate flight paths, but also other factors including theextent to which acceptable sensor coverage will be obtained, whilst alsoensuring that the paths do not pass through no-fly zones or lead topotential violations of a minimum safe altitude above terrain. Toachieve this, at step 540 the processing system 201 compares thecandidate flight paths to the elevation data and to no-fly data,indicative of no-fly zones, such as restricted airspace. The processingsystem 201 uses the comparison to detect potential intersects witheither elevation or no-fly zones, with potential intersects then beingused to determine a first score, with any intersecting paths being givena low first score.

At step 545, the processing system 201, calculates sensor coverage foreach of the candidate flight paths, which takes into account whether theinfrastructure would be located within a sensor field of view FOVdependent on a lateral extent of the sensor footprint, as shown for theaircraft A in FIG. 5E. It will be appreciated that this can depend onfactors such as the roll angle of the aircraft, or the lateral offsetbetween a centre line of the aircraft and the infrastructure, asdetected from on board aircraft sensors. In one example, if theon-survey paths are linear, the roll angle can be assumed to be zero, inwhich case the relative lateral position of the aircraft andinfrastructure segment alone can be used to determine whether theinfrastructure is within the field of view. Once this has beendetermined, for each candidate flight path, the proportion of theinfrastructure that is within the field of view of any of the on-surveypaths in the candidate flight path is used to generate a second score.It will be appreciated however that other measures such as the amount oftime the infrastructure is within the field of view could be used.

Similarly, the path length is used to determine a third score, with thethird score being lower for longer path lengths. The processing system201 then combines the first, second and third scores, to generate anoverall score for each candidate flight path at step 550. Thus, thescore will be formed from components dependent on the path length, pathintersects with terrain and no-fly zones and infrastructure sensorcoverage, with paths being given a low score if there are intercepts,poor sensor coverage or long path lengths.

It will be appreciated that the calculation of an overall score can beperformed in any manner, and that this can vary depending on theimplementation. Furthermore, the individual scores and their combinationcan be determined to reflect the relative importance of the differentfactors, so different weightings could be applied to different scores.For example, the calculation would typically be performed so that acandidate flight path with good sensor coverage but intersects withterrain, would not be selected in preference to a candidate flight pathhaving poorer sensor coverage but no intersects.

In any event, at step 555, the processing system 201 selects a new bestcandidate flight path using the score, which in this case is thecandidate flight path with the highest score for the current iteration,and then compares this to a current best flight path, which is the bestcandidate flight path from previous iterations, at step 560.

At step 565 the processing system 201 determines if the new bestcandidate flight path is better than the current best flight path, andif so replaces the current best flight path with the new best candidateflight path at step 570. In this regard, it will be appreciated that onthe first iteration the new best candidate flight path becomes thecurrent best flight path, whereas on subsequent iterations this willonly occur if the new best candidate flight path has a better score thanthe current best flight path.

In either case, at step 575 the processing system 201 determines if astop condition has been reached. A stop condition will typicallycorrespond to a predetermined number of iterations, or alternatively apredetermined improvement (or lack of improvement) of the current bestflight path over a set number of iterations, and is used to terminatethe iterative process at suitable point when no further meaningfulimprovement is being obtained.

If the stop condition has not been reached, then the processing system201 modifies the set of on-survey flight paths at step 580. Inparticular, the processing system 201 will use predetermined rules inorder to modify the agents representing the on-survey paths. It will beappreciated that in the above described process any candidate paths areretained. However, the agents are modified so that at each iteration,the worst solutions gradually approach the best solution so that withincreasing number of iterations, the gap between worst and bestsolutions becomes smaller and smaller. The modification is typicallyperformed based on the agents used for determining the current bestflight path, or the best candidate flight paths identified in previousiterations, so that attributes of the best candidate flight pathspropagate to the agents of the candidate sets in the next iteration.This helps progressively improve the candidate flight paths on eachiteration, thereby optimising the resulting flight paths, as will beappreciated by persons skilled in the art.

Once the sets have been modified the process returns to step 520,allowing off-survey paths to be determined for each of the modifiedsets.

Once a stop condition is reached, the processing system 201 uses thecurrent best flight path to define the flight path that will be used bygenerating path data including a sequence of on-survey paths. This pathdata can then be stored for subsequent transfer to the aircraft at step590.

The above described process may utilise individual modules in order toperform different aspects of the flight planning method. In particular,the processing system 201 can implement a mission planning module inorder to identify segments and group these into missions at step 505 and510. A survey optimiser module can be used for optimising the survey byperforming steps 515 and 540 onwards, whilst a survey path planningmodule is used for identifying the candidate flight paths at steps 520to 535. However, this is not essential and any suitable processes ordelineation of tasks can be used.

An example of apparatus for controlling an aircraft will now bedescribed with reference to FIG. 6.

In this example, an apparatus includes an aircraft processing system601, which is coupled to a sensor 620 defining a field of view FOV, suchas a LiDAR system, and a flight control system 630 such as a commercialautopilot or the like.

The aircraft processing system 601 includes an electronic processingdevice, such as at least one microprocessor 610, a memory 611, anoptional input/output device 612, such as a touch screen display, and anexternal interface 613, interconnected via a bus 614 as shown. In thisexample the external interface 613 can be utilised for connecting theaircraft processing system 601 to the flight control system 630 andsensor 620, and optionally to communications networks 202, 204, or otherstorage devices, or the like. Although a single external interface 613is shown, this is for the purpose of example only, and in practicemultiple interfaces using various methods (eg. Ethernet, serial, USB,wireless or the like) may be provided.

In use, the microprocessor 610 executes instructions in the form ofapplications software stored in the memory 611 to perform requiredprocesses, such as using path data to generate control signals for theflight control system. Thus, actions performed by the aircraftprocessing system 601 are performed by the processor 610 in accordancewith instructions stored as applications software in the memory 611and/or input commands received via the I/O device 612, or commandsreceived from other processing or computer systems 201, 203. Theapplications software may include one or more software modules, and maybe executed in a suitable execution environment, such as an operatingsystem environment, or the like.

Accordingly, it will be appreciated that the aircraft processing system601 may be formed from any suitable processing system, such as asuitably programmed computer system. In one particular example, theaircraft processing system 601 is custom hardware specificallyconfigured to interface with flight control systems, and could thereforeinclude any electronic processing device such as a microprocessor,microchip processor, logic gate configuration, firmware optionallyassociated with implementing logic such as an FPGA (Field ProgrammableGate Array), or any other electronic device, system or arrangement. Inone further example, the aircraft processing system 601 could beequivalent to a computer system 203 described with respect to FIG. 2,and coupled to the communications networks using wireless networks.

Operation of the apparatus of FIG. 6 for controlling an aircraft willnow be described with reference to FIGS. 7A and 7B. For the purpose ofthis example, it is assumed that the aircraft processing system 601 hasbeen provided with the path data generated at step 590 in the abovedescribed process, with this having been pre-loaded into the memory 611,or another accessible data store.

In this example, at step 700 the aircraft processing system 601determines a current aircraft position. This information is typicallyobtained from on board aircraft flight sensors, such as from on inbuiltor peripheral Global Navigation Satellite System (GNSS) receivers,inertial sensors, or the like.

At step 705, the aircraft processing system 601 determines a current andnext on-survey path from the path data. In particular, in aircraftprocessing system 601 will use the current position to identify wherethe aircraft is in respect of the path data, and then select the currentand next on-survey paths. The aircraft processing system 601 will thencalculate any off-survey path linking the current and next on-surveypaths using the aircraft flight path model, at step 710. In this regard,it will be appreciated that an off-survey path may not be required inthe event that the on-survey paths are directly interconnected, forexample if an off-survey path having a zero length was identified in theoptimisation process.

At this point the aircraft processing system 601 can optionally checkwhether this path results in any intersects with any terrain or no-flyzones. Whilst this should not occur as the particular sequence ofon-survey segments have been selected so that flight path does notinclude intersects, it will be appreciated that sometimes no fly zonescan be updated in real-time, for example based on weather patterns orthe like. For example, in the event that a storm arises in the localarea, this could be notified to the processing system 601, eithermanually or through automatic updates and interpreted as a no-fly zone.In the event that an intersect arises, an alarm or other notificationcould be used to alert the pilot, with the flight path being modifiedeither manually by the pilot or automatically by the processing system601, as required.

Assuming there are no intersects, at step 715 the aircraft processingsystem 601 generates control signals, which are transferred to theflight control system 630. At this point the processing system may alsoupdate a user interface displayed by the display 612, an example ofwhich is shown in FIG. 7C.

The user interface is generated to show the pilot information regardingthe current flight path, including the position of on-survey segmentsand the off-survey flight path. This assists the pilot in ensuring thatthe flight path is being correctly followed by the aircraft. The userinterface includes a number of indicators and controls including:

-   -   a previous page input 761 for moving back one page;    -   a system state indicator 762 to indicate whether the aircraft is        transiting or recording;    -   a flight indicator 763 to indicate a departure airfield and        heading information;    -   a survey progress indicator 764 to show the progress on the        current survey;    -   a time indicator 765 to indicate a current elapsed and/or        remaining mission time;    -   a message indicator 766 to display pilot messages and alerts;    -   a next page input 767 to allow a next page to be selected;    -   a map zoom in button 768;    -   a map zoom out button 769;    -   a select next waypoint input 770 to show the next un-surveyed        on-survey path;    -   a select previous waypoint input 771 to show the previous        un-surveyed on-survey path;    -   a map overview input 772 to view an active flight plan for        summary purposes;    -   a ground speed indicator 773;    -   a cross track error indicator 774 to display an error between        the current track and planned track;    -   an sensor height above ground (AGL) estimate 775;    -   a magnetic heading 776;    -   an aircraft current position indicator 777 which displays the        current GPS (Global Positioning System) position of the        aircraft; and    -   a current on-survey path indicator 778;    -   an off-survey path indicator 779; and,    -   a next on-survey path indicator 780.

The display can also include range rings to assist situational awarenessas well as other pertinent information, as will be appreciated bypersons skilled in the art.

At step 725, the aircraft processing system 601 ascertains whether theaircraft is currently or will soon be flying over on-survey segment. Ifnot, the processing system 601 ensures the sensor is deactivated at step730, returning to step 700 to determine a current aircraft position andrepeat the above described process. If the processing system 601determines the aircraft is on an on-survey segment, then at step 735 theaircraft processing system 601 ensures the sensor 620 is active so theinfrastructure is sensed.

Thus, it will be appreciated that the above steps leave the sensoractivated whilst the aircraft is on an on-survey path, deactivating thesensor as the aircraft leaves the on-survey and enters the off-surveypath and reactivating the sensor when the aircraft returns to anon-survey path, thereby ensuring that sensing is only performed asrequired.

When on an on-survey path, at step 740 the aircraft processing system601 will perform monitoring confirm whether infrastructure is beingsensed at step 745. This can be achieved by monitoring the sensor andusing recognition algorithms to ensure infrastructure can be identifiedin any sensed data. Alternatively this can be achieved by performing ageometrical check based on the current aircraft position, roll, pitch,and yaw, combined with knowledge of the field of view of the sensor, andknown position of the infrastructure. If a positive indication isdetermined, the aircraft processing system 601 returns to step 700allowing a current aircraft position to be monitored and the processrepeated. If not however, the aircraft processing system 601 can triggera go-around by reselecting current on-survey path as the next on-surveypath returning then to step 710 to determine an off-survey pathinterconnecting to the current on-survey path to trigger a go-around.

Accordingly, in the above described process the aircraft processingsystem 601 uses path data generated by the processing system 201 togenerate off-survey paths, which are in turn used to control theaircraft by generating suitable control signals for the flight controlsystem. In one example, this can be achieved by having the aircraftprocessing system 601 implement at least a survey path planning modulesimilar to that described above. More typically however, the aircraftprocessing system further implements a survey optimiser module as well,allowing the flight path to be dynamically updated as required, forexample to allow for go-arounds as well as to accommodate no-fly zonechanges. It will be appreciated from this that the aircraft processingsystem 201 could also operate to plan flight paths based on receivedcoordinate and elevation data, in which case separate ground basedplanning is not required.

Nevertheless separate ground based planning can be desirable for anumber of reasons. For example, this can be used to define missions forimplementation by different aircraft, ensuring the missions defined areappropriate and properly allocated to different aircraft. This can alsoallow for submission of flight plans in advance of flights occurring, aswell as allowing a reduced computational load to be used during flight.

In any event, it will be appreciated that the above described method andapparatus allow for planning of infrastructure survey flights that takeinto account elevation data, thereby allowing aircraft altitude to becontrolled, which in turn reduces demands on the pilot. The processfurther uses optimisation of both on and off survey paths, improving theoptimisation process, and providing flight path solutions that could nothave been obtained using previous optimisation techniques. For example,this could allow for flying perpendicularly relative to theinfrastructure as part of an on-survey path, which is a flight plan thatwould not be accommodated in existing systems. This can be useful in avariety of situations, for example, if there are infrastructure segmentsarranged in parallel, to avoid intersects with terrain/no-fly zones,and/or to result in shorter flight paths.

A specific example of a 3D Linear Infrastructure Pilot Flight AssistSystem (3D PFAS) will now be described in more detail with reference toFIG. 8.

In this example, the system includes two major components, namely theground based planning system 810 and an onboard flight control system820. The ground based planning system 810 includes a processing system,such as a suitably programmed computer system including a missionplanning module 811, an on-off survey optimiser 812 and an on-off surveypath planner 813. These modules operate to plan the flight paths andgenerate flight path data, which can be transferred for example using aremovable storage media 830, to the onboard flight control system 820.The onboard flight control system 820 is typically a processing system,such as a computer system that implements a real-time on-survey pathselector 821, a real time off-survey path planner 822, a real timesurvey planning, sensor control and capture quality assurance module823, and a control guidance module 824. The onboard flight controlsystem 820 interfaces with a commercial autopilot system 840 and sensor850, to control flight of the aircraft 860 and sensor operation.

Each of the modules will now be described in more detail. For thepurpose of illustration reference will be made to previous 2D flightplanning techniques, with distinctions and benefits being highlighted asappropriate. In this regard, improvements over existing 2D system thatare highlighted include automated on and off-survey path planning,automated 3D path planning, automated 3D guidance including position,roll, pitch, yaw, altitude, speed and sensor control, and in-flightreplanning. It will be appreciated however that each of these are notessential.

The mission planner 811 retrieves data from a database 814 includinglinear segments (represented by spatial coordinates) describing linearfeatures of the infrastructure 814.1 to be inspected, and uses aniterative bin-packing and sorting process to group into a set ofuser-defined time long inspection plans. This process operates on linearsegments describing features to be inspected, as opposed to using manualtechniques as occurs in traditional, including 2D, approaches.

In the 2D approaches the path planning approach is to treat the problemas a combinatorial optimization problem and solve by using a routesequencer. The underlying scientific methodology of the 2D PFAS approachis to manually define a set of on-survey paths by considering the linearinspection objectives to be met (and sensor footprint coverageconstraints), formulate as a combinatorial optimization problem andemploy an automated route sequencing approach, which results in anoptimized sequence of on-survey paths with calculated off-survey pathsin between forming a global flight path.

In contrast, the on-off survey optimizer 812 formulates the task as acontinuous optimization problem, and uses a model of the sensorfootprint to allow the algorithm to define a path consisting of straightline segments defining on-survey paths and off-survey paths, which arecalculated by an aircraft flight path model, using sensor coveragerequirements as constraints on the global path.

Unlike the 2D approach, the 3D PFAS approach can provide fully automatedpath planning and requires no manual input or assistance in definingon-survey paths which achieve coverage of the linear inspectionobjectives. Such an approach will work in 2D, 3D or higher space.However higher planning dimensions introduces increased computationalworkload which may only be achieved by high performance computingsystems.

In this example, the on-off survey optimiser uses artificialintelligence techniques with an aircraft flight path model and sensorfootprint model to determine the best global path which minimizes flightdistance whilst achieving coverage of inspection objectives. Such AItechniques can include EA (Evolutionary Algorithm) processes (e.g.micro-GA (Genetic Algorithm)), which mimic biological evolutionaryprocesses, or firefly optimization which mimics the way in which fireflyinsect swarms attract to and locate a light source. Such continuousoptimizers operate by defining an individual yet cooperative agent(gene, firefly, or otherwise), with a pool or population set of suchagents constituting candidate on-survey path solution sets. In oneexample, each agent describes a set of N on-survey paths, with eachagent including information about how many on-survey paths there are(N), and the locations of these paths. Each agent can describe adifferent number of on-survey paths, as well as different lengths,positions, and orientations.

The next step is to evaluate the off-survey paths for this given set ofcandidate on-survey paths using the aircraft flight path model, and thecoverage of linear tasks using the electro-optical sensor footprintmodel. The coverage constraints include the requirement that the sensorfield of view must overlay every part of the linear infrastructure to beinspected within a user-defined coverage tolerance (e.g. 99.9%). Theoptimizer then continually evaluates costs and constraints, utilizingthe AI search technique employed, and stops when either a predefinednumber of iterations or defined tolerance is reached. The definedtolerance could be of any suitable form and could be based on adifference between previous best and current worst solutions, a definedrate of change of the scores, or the like. The output of this process isa complete on-survey and off-survey path which achieves inspection ofthe linear infrastructure within defined coverage tolerance.

Thus, the on-off survey path planner 813 plans paths for each set ofagents defined by the optimiser, allowing the optimiser to evaluate theplanned paths and iteratively improve the agent combinations. In 2Dsystems only off-survey planning and route sequencing is performedbecause on-survey paths are determined by manual process. In the currentsystem however, the on-off survey path planner determines both on-surveyand off-survey paths as part of the on-off survey optimizer process.

Within a framework of AI continuous optimization—on-survey paths aredefined as the linear links between autonomous biological agents.Off-survey paths are the aircraft dynamic links between on-survey pathsin the pool or population of agents. An example implementation ofoff-survey path planning is as follows: The off-survey path plannertakes an individual set of agents, which includes a set of N on-surveysegments, and for every possible combination of on-survey segments andtheir reverse direction (on-survey segments are bi-directional),calculates the length of the off-survey path using geometric 3D pathplanning techniques, with consideration of aircraft heading rateconstraint and speed, which describes the aircraft maximum bank angle,and minimum turn radius (or path curvature) constraint, requiredaltitude above terrain and linear features, flight path angle and rateof climb speed of the aircraft. It also calculates potential pathcollisions of on-survey or off-survey paths with terrain or no-flyregions using digital elevation model and/or no-fly regionspecification. The complete global path is simply the set of on-surveypaths with linking off-survey paths.

In one example, the techniques for 3D path generation can be based uponKok, Jonathan, Bruggemann, Troy S., & Gonzalez, Luis F. (2013) “Anevolutionary computation approach to three-dimensional path planning forunmanned aerial vehicles with tactical and kinematic constraints”, inproceedings of the 15th Australian International Aerospace Congress,Melbourne Convention Centre, Melbourne, VIC, but with the techniquesextended beyond off-survey path planning only to include both on andoff-survey paths.

The real-time on-survey path selector 821 takes the path data ofon-survey segments and the optimized sequence of on-survey segments(tour), and loads into the flight computer via USB (or other suitablemechanism such as an over-the-air mobile data connection). In thisregard, only loading the on-survey segments into the flight computer canbe used to save data storage (corresponding to the planned inspectionactivity that might occur during next flight).

The current position of the aircraft is known at frequent intervals fromthe commercial navigation system. Starting from the first on-surveysegment of the path sequence list, the current and the next on-surveypath is selected from the list.

The real-time off-survey path planner 822 plans 3D off-survey paths inreal-time for control system guidance purposes. In this example, thesame off-survey path planning algorithm implemented by the on-off surveypath planner 813 is used, although different algorithms could be used.In this example however, the off-survey paths are calculated withrespect to current position of the aircraft (in real-time), whereas theon-off survey path planner 813 operates based upon the expected positionof the aircraft (at the ends of on-survey paths).

During off-survey stages of an inspection flight, the current locationof the aircraft is used to calculate in real-time the optimizedoff-survey path between current location and next on-survey segment.This off-survey path is re-calculated at each time instant to findoptimized path to next stage of inspection. Continual re-calculated ofthe optimize off-survey path allows the aircraft system to effectivelyand efficiently compensate for unexpected deviations from plannedtrajectories (such as might be caused of extreme wind gusts). Thecurrently calculated version of the planned off-survey path is stored asa sequence of spatial coordinates within the flight computer, and alsodisplayed on a flight display.

The real-time survey planning, sensor control and capture qualityassurance module 824 operates to automatically control the sensor,including on-off data capture control by sending commands to the LiDARcamera system to activate or deactivate the logging of data depending onwhether the aircraft is in the on-survey or off-survey mode. Thisautomatic control of the data capture reduces the burden on the pilotand can completely obviate the need for a second operator in theaircraft to manually control the LiDAR and camera sensor as occurs intraditional techniques.

Additionally, the module provides for automatic quality assurancemonitoring of data capture swath for compliance with target captureregion. This element uses real time LiDAR information with positioningand orientation data from the GPS and IMU (Inertial Measurement Unit)outputs from the sensor system to calculate whether the desired area ofinterest has been captured within the LiDAR sensor swath. The module canalso use this to perform automatic triggering of a re-survey conditionif the desired capture region has fallen outside of the LiDAR sensorswath by automatically triggering a flight “go-around” condition, whichcommands the aircraft to re-fly that particular on-survey path segment.The on-off survey logic uses the current position of the aircraft (asknown from the commercial navigation system) to determines whether it ison an on-survey path or an off-survey path and selects the planned pathfrom either the real-time on-survey paths selector 821 or the real-timeoff-survey path planner 822, for command into the control guidancemodule 824.

The control guidance module 824 achieves tracking of the planned path,with horizontal and vertical dynamics of the aircraft being consideredseparately.

For horizontal guidance a fictitious receding virtual waypoint (RVWP) isplaced on the planned path at a pre-designed fixed distance and movesahead of and with the aircraft position. This is similar to the approachin Bruggemann, Troy S., Ford, Jason J., & Walker, Rodney A. (2010)“Control of aircraft for inspection of linear infrastructure”. IEEETransactions on Control Systems Technology, 19(6), pp. 1397-1409.

In the horizontal guidance approach, based upon the current position ofthe RVWP and the aircraft, the guidance module uses a guidance algorithmto determine the roll angle which minimizes the cross-track error to thepath such that precise tracking of the path is achieved. A command (inthe form of either roll angle, heading angle, or heading angle-rate) isthen sent to the autopilot which executes the command through movementof control surfaces via actuator (aileron) resulting in aircraft rollingmotion. If the aircraft moves over the end of the current segment, thecurrent segment is flagged as inspected, and the current and nextsegments are updated by stepping to the next on-survey segments listedin the sequence list. This process is repeated, until all segments inthe sequence list are inspected. After the tour is inspected, themission is defined to be complete.

A number of other functions can also be implemented, including checkingfor inspection compliance by considering sensor field of view whenflying in on-survey mode. In this instance, a modelled sensor field ofview is utilized to check for inspection compliance. If the inspectionfeature lies outside of the modelled sensor field of view, a go-aroundmanoeuvre is triggered and a real-time off-survey path is calculatedfrom the last inspected on-survey segment.

The control guidance module 824 can also ensure inspection compliance inadvance of flying across on-survey corners by examining if the on-surveypath changes direction (such as the case when line segments are joined)and this heading change is larger than a certain limit, in which case aturn around the corner manoeuvre can be planned through modification ofthe flight path that ensures the corner between on-survey segments arewithin the modelled sensor field of view.

Additionally the control guidance module 824 provides for verticalguidance by providing vertical guidance commands for throttle and/orelevator actuator settings to achieve desired altitude and speedsettings. In one example, this involves back-stepping elevator controlwith feed-forward throttle techniques or other similar elevator andthrottle control techniques, as described for example in OnvareeTechakesari, Troy Bruggemann and Jason J. Ford, “Vertical channelguidance for infrastructure inspection”, Proc of AUCC-2013, November,2013.

The onboard flight control system 820 can also include a display 825.The display includes basic information provided in previous 2D systems,as well as the necessary vertical path, altitude, speed and pitchinformation. The display 825 typically shows inspection progress, sensoroperating mode, aircraft flight mode, planned 3D trajectory and currentaircraft location, with desired and current speed, pitch and altitude.The display can be used to allow the pilot to select a flight plan toactivate, pause a current flight plan, etc.

The onboard flight control system 820 interfaces with a commercial 3Dautopilot system 840 which accepts heading, roll, or heading rate, pitchand throttle or speed commands.

In the above described system, the functionality is separated betweenthe ground based planning system 810 and an onboard flight controlsystem 820, with data being transferred manually therebetween. However,this is not essential and alternative arrangements could be used.

For example, data could be transferred automatically between the groundbased planning system 810 and an onboard flight control system 820. Thiscould be achieved using a communications network, or the like, withtransfer being upload (push) from the ground based planning system ordownload initiated from the aircraft (pull).

The ground based planning system 810 and an onboard flight controlsystem 820 could be integrated into a single onboard system to enableon-board path planning and direct integration with thein-flight/real-time computer and sensor control system to enable thedirect generation and rerouting of revised new flight paths for pilotinitiated events and/or in circumstances such as no fly regions, severeweather events, air traffic, unplanned infrastructure capture or othersituation requiring a change to the planned mission. Such an event maybe triggered via external sensory means or by pilot intervention.

Furthermore, whilst the above described system is used to generatecontrol signals for a flight control system, such as an autopilot, thisis not essential, and alternatively the system could be integrated intoan autopilot, thereby providing an integrated ‘all in one’ package andeliminate physically separate interconnected components.

Whilst the above described arrangements have focused on implementationin pilot controlled systems, this is also not essential, andalternatively, the systems could be implemented in Unmanned AerialVehicles (UAVs), remotely monitored and piloted aerial vehicles and/ordrones.

The system may also utilise positioning and related inertial measurementparameters provided to the aircraft remotely through communicationnetworks or other data transmission or other means.

Additionally, the sensor could be of any form and reference to LiDAR asone example is not intended to be limiting.

In any event, it will be appreciated that the above described systemsprovide mechanisms that allow for flight planning and control ofaircraft that can address deficiencies of existing systems.

For example, the process can addresses the limitations of previoussystems through the use of iterative processes, for example usingbiologically modelled optimisation methods, including combinatorialtechniques, to determine an optimized 3D flight path with considerationof aircraft dynamic constraints in 3D, spatial and orientation sensorfield of view constraints and terrain/no-fly regions.

In previous systems, once a flight path had been developed, the pilothad to attempt to fly the desired path whilst simultaneously maintainingaircraft pitch (altitude), air speed and otherwise monitor aircraftsurrounds at low altitude (sub 2000 m), which in placed a high anddemanding load on the pilot and consequently was only practicable forshort periods of duration. Additionally, the ability of the pilot tocontrol the aircraft and consistently achieve the target path is highlyvariable and subject to pilot experience and other human factors such asfatigue. Limitations in existing commercial autopilot systems also failsto consider tracking of a path for linear infrastructure inspection,designed with sensor field of view constraints and aircraft dynamics,being designed primarily for waypoint to waypoint navigation, take-off-,holding pattern, or landing tasks.

In contrast, the above described examples can provide control for flightguidance, including position, roll, pitch, yaw, altitude and speed, aswell as LiDAR/Imaging Sensor or deployment control, by interfacing withexisting commercial auto pilot systems. This assists the pilot bycontrolling the banking of the aircraft to make the necessary turns andclimbs as required to follow the desired flight path, in addition tocontrolling altitude and speed to achieve the required height and speedabove the infrastructure for safety and successful data capture, whilstavoiding terrain or no-fly zones. This allows the pilots to fly along acarefully planned trajectory, whilst reducing the pilot workloadrequirements to control the airspeed and altitude and achieve inspectionobjectives in the presence of terrain or no-fly zones, and removes thevariability of data capture process.

In one example, the process can provide automated on and off-survey pathplanning, automated 3D path planning, automated 3D guidance andin-flight replanning capabilities.

Automated holistic on and off-survey path planning can streamline theprocess efficiencies and remove the necessity for manual input. This canlead to improvements in dynamic flexibility in the flight planningprocesses (on-survey paths can easily be modified to accommodate terrainor no-fly zone considerations), and the possibility for shorter flightpaths by planning both on and off-survey paths simultaneously, forexample by allowing paths that do not follow infrastructure directly,but allow for lateral flying relative to infrastructure, which is usefulfor example when sensing junctions between network spurs, or parallelspaced apart infrastructure segments.

Automated 3D path planning reduces operator/pilot workload and bringsmore efficient planning, efficient data capture and improved safety.This is performed by providing an automated 3D path planning capabilityby automating the process of finding the shortest flight path whichachieves linear inspection objectives, whilst considering aircraftdynamic (turn and climb) constraints, inspection sensor operatingparameters (required operating speeds, altitudes and 3D orientation), 3Dterrain and no-fly zone environment.

Providing an automated 3D flight guidance capability by automated turn,speed and altitude control reduces pilot in-flight workload, ensuresefficiency of data capture, and safety is improved by autonomouslyguiding around terrain and no-fly regions.

Providing the ability to replan existing flight paths in 3D, such asrequired, for example, if a severe weather pattern covers part of thelinear inspection task region, and on-survey and off-survey pathplanning reconfiguration is required (such as reorientate,shorten/lengthen, realign, add or remove on-survey paths, and update theassociated impacts on the planned off-survey paths).

Thus, the above described processes can provide algorithms forautomatically generating 3D flight paths for an aircraft that achieves adesired inspection purpose (sensing of nearly linear infrastructure),whilst also ensuring safe flight. Given infrastructure data, the systemcan automatically design both on-survey and off-survey flighttrajectories under consideration a range of design considerations,including avoidance of non-flyable flight areas such as coast regions,natural terrain barriers, and any prohibited flight areas; feasibilityof flight path from aerodynamic perspective, limitations of availableflight control systems, whilst ensuring efficient inspection time.

As a result, the above described methods and apparatus can providegreater performance and improved operational efficiencies compared totraditional techniques, including reduced manual intervention in thepath planning process, optimisation of path planning techniquesresulting in reduced flight paths, reduced pilot workload throughincreased levels of autonomy and control of altitude and aircraft speedvia developed system, an ability for the system to automatically alterand recalculate flight paths ‘on-aircraft’ in response to changingcapture conditions, resulting in better network capture and reduced needto otherwise plan and re-fly network, the ability to generate and fly 3Dflight plans, making the system more suitable to undulating terrain andexpanding geographic/market areas for utilisation of the technology.

Throughout this specification and claims which follow, unless thecontext requires otherwise, the word “comprise”, and variations such as“comprises” or “comprising”, will be understood to imply the inclusionof a stated integer or group of integers or steps but not the exclusionof any other integer or group of integers.

Persons skilled in the art will appreciate that numerous variations andmodifications will become apparent. All such variations andmodifications which become apparent to persons skilled in the art,should be considered to fall within the spirit and scope that theinvention broadly appearing before described.

1. A method of developing a flight path for precision flying over anarea of interest, the method including, in an electronic processingdevice: a) determining coordinate and elevation data relating to an areaof interest; b) using the coordinate and elevation data to determine aflight path including: i) precision paths corresponding to precisionflying trajectories; and, ii) non-precision paths interconnecting atleast some of the precision paths; and, c) generating path data at leastpartially indicative of the flight path, the path data being useable ingenerating control signals for at least partially controlling operationof the aircraft, in use.
 2. A method according to claim 1, wherein theprecision paths are for at least one of: a) sensing at least part of thearea of interest; and, b) deployment into the area of interest. 3.(canceled)
 4. A method according to claim 1, wherein the methodincludes, in the electronic processing device, determining the flightpath at least in part using an aircraft flight path model and at leastone of sensor coverage and deployment parameters and wherein the methodincludes: a) determining a plurality of candidate precision path sets;b) for each candidate precision path set, determining a candidate flightpath; and, c) selecting a best candidate flight path from the candidateflight paths.
 5. (canceled)
 6. A method according to claim 4, whereinthe method includes, in the electronic processing device, for eachcandidate precision path set: a) determining non-precision paths betweenpairs of precision paths using an aircraft flight path model; b) foreach possible sequence of precision paths, calculating a length of apossible flight path; and, c) selecting the possible flight path withthe shortest flight path length as the candidate flight path. 7.(canceled)
 8. A method according to claim 6, wherein the methodincludes, in the electronic processing device, using the aircraft flightpath model to calculate a candidate non-precision path using at leastone of: a) aircraft heading rate constraint and speed; b) an aircraftmaximum bank angle; c) an aircraft minimum turn radius; d) a requiredminimum altitude above the area of interest; e) flight path angle; andf) rate of climb speed of the aircraft.
 9. A method according to claim8, wherein the method includes, in the electronic processing device: a)determining a score for each candidate flight path in accordance with atleast one of: i) intersections with terrain using the elevation data;ii) intersections with no-fly zones using no-fly zone data indicative ofthe no-fly zones; iii) at least one of sensor coverage and deploymentparameters; and iv) a flight path length; and, b) selecting the bestcandidate flight path using the score.
 10. (canceled)
 11. A methodaccording to claim 4, wherein the method includes, in the electronicprocessing device: a) iteratively determining a plurality of bestcandidate flight paths; and, b) selecting one of the plurality of bestcandidate flight paths as a best flight path.
 12. A method according toclaim 11, wherein the method includes, in the electronic processingdevice, at least one of: a) modifying the candidate precision path setsfor each iteration; b) for each iteration: i) comparing a best candidateflight path to a current best flight path; and, ii) selectively updatingthe current best flight path with the best candidate flight pathdepending on the results of the comparison; and, c) iterativelydetermining best candidate flight paths until at least one of: i) adefined number of iterations have been performed; and, ii) a definedtolerance is reached.
 13. (canceled)
 14. (canceled)
 15. A methodaccording to claim 1, wherein the path data includes: a) precisionsegment data indicative of precision paths; and, b) an precision pathsequence indicative of an order in which precision paths should beflown.
 16. A method according claim 1, wherein the path data is used incontrolling at least one of: a) a pitch and altitude of the aircraft inuse; b) at least one of a roll, yaw, airspeed and engine power of theaircraft in use; and, at least one of a sensor and a deployment device.17. (canceled)
 18. (canceled)
 19. A method according to claim 1, whereinthe method includes, in the electronic processing device: a) determininga current aircraft position; and, b) calculating the flight path basedon the current aircraft position.
 20. Apparatus for developing a flightpath for precision flying over an area of interest, the apparatusincluding an electronic processing device that: a) determines coordinateand elevation data relating to an area of interest; b) uses thecoordinate and elevation data to determine a flight path including: i)precision paths corresponding to precision flying trajectories; and, ii)non-precision paths interconnecting at least some of the precisionpaths; and, c) generates path data at least partially indicative of theflight path, the path data being useable in generating control signalsfor at least partially controlling operation of the aircraft, in use.21. A method of controlling an aircraft for precision flying over anarea of interest, the method including, in an electronic processingdevice: a) determining path data at least partially indicative of aflight path, the flight path including precision paths corresponding toprecision flying trajectories and non-precision paths interconnecting atleast some of the precision paths; and, b) generating control signalsfor at least partially controlling at least one of the attitude, roll,pitch, speed and altitude of the aircraft using the path data, whereinthe method includes, in the electronic processing device: i) determiningif the aircraft is on a precision path; and, ii) selectively activatingand deactivating a sensor depending on results of the comparison; iii)monitoring the sensor; iv) determining if the area of interest has beensensed; and, v) if not, modifying the flight path. 22-31. (canceled) 32.Apparatus for controlling an aircraft for precision flying over an areaof interest, the apparatus including an electronic processing devicethat: a) determines path data at least partially indicative of a flightpath, the flight path including precision paths corresponding toprecision flying trajectories and non-precision paths interconnecting atleast some of the precision paths; and, b) generates control signals forat least partially controlling at least one of the attitude, roll,pitch, speed and altitude of the aircraft using the path data, whereinthe electronic processing device: i) determines if the aircraft is on aprecision path; and, ii) selectively activates and deactivates a sensordepending on results of the comparison; iii) monitors the sensor; iv)determines if the area of interest has been sensed; and, v) if not,modifies the flight path.
 33. A method of developing a flight path forprecision flying over an area of interest, the method including, in anelectronic processing device: a) determining a flight path by optimisinga combination of precision paths corresponding to precision flyingtrajectories and non-precision paths interconnecting at least some ofthe precision paths; and, b) generating path data at least partiallyindicative of the flight path, the path data being useable in generatingcontrol signals for at least partially controlling operation of theaircraft, in use.
 34. A method according to claim 33, wherein the methodincludes, in the electronic processing device: a) determining aplurality of candidate precision path sets; b) for each candidateprecision path set, determining a candidate flight path; and, c)selecting a best candidate flight path from the candidate flight paths.35. A method according to claim 34, wherein the method includes, in theelectronic processing device, for each candidate precision path set: a)determining non-precision paths between pairs of precision paths; b) foreach possible sequence of precision paths, calculating a length of apossible flight path; and, c) selecting the possible flight path withthe shortest flight path length as the candidate flight path.
 36. Amethod according to claim 35, wherein the method includes, in theelectronic processing device determining candidate non-precision pathsusing an aircraft flight path model by calculating a candidatenon-precision path using at least one of: a) aircraft heading rateconstraint and speed; b) an aircraft maximum bank angle; c) an aircraftminimum turn radius; d) a required minimum altitude above the area ofinterest; e) flight path angle; and f) rate of climb speed of theaircraft.
 37. (canceled)
 38. A method according to claim 34, wherein themethod includes, in the electronic processing device: a) determining ascore for each candidate flight path in accordance with at least one of:i) intersections with terrain using the elevation data; ii)intersections with no-fly zones using no-fly zone data indicative of theno-fly zones; iii) at least one of sensor coverage and deploymentparameters; and, iv) a flight path length; and, b) selecting the bestcandidate flight path using the score.
 39. (canceled)
 40. A methodaccording to claim 34, wherein the method includes, in the electronicprocessing device: a) iteratively determining a plurality of bestcandidate flight paths; and, b) selecting one of the plurality of bestcandidate flight paths as a best flight path.
 41. A method according toclaim 40, wherein the method includes, in the electronic processingdevice, at least one of: a) modifying the candidate precision path setsfor each iteration, b) for each iteration: i) comparing a best candidateflight path to a current best flight path; and, ii) selectively updatingthe current best flight path with the best candidate flight pathdepending on the results of the comparison; and, c) iterativelydetermining best candidate flight paths until at least one of: i) adefined number of iterations have been performed; and, ii) a definedtolerance is reached.
 42. (canceled)
 43. (canceled)
 44. Apparatus fordeveloping a flight path for precision flying over an area of interest,the apparatus including an electronic processing device that: a)determines a flight path by optimizing a combination of precision pathscorresponding to precision flying trajectories and non-precision pathsinterconnecting at least some of the precision paths; and, b) generatespath data at least partially indicative of the flight path, the pathdata being useable in generating control signals for at least partiallycontrolling operation of the aircraft, in use. 45-88. (canceled)